The present invention relates to a cassette reel lock and, more particularly, to an improved reel lock and locking mechanism for locking the reels of a tape cassette.
Various locking mechanisms have been employed in the past for locking the reels of video tape cassettes when the cassettes are not installed in the recording or playback machines, for example, when the cassettes are being transported. Such locking mechanisms prevent the accidental unwinding and tangling of the tape when the cassettes are not in use.
Several prior reel locking mechanisms are disclosed, by way of example, in U.S. Pat. Nos. 4,195,797 and 4,232,840. These prior locking mechanisms employ locking members which are rotatable into and out of reel engagement and are urged into the reel engaging position by separately installed metal springs. Such separately installed springs have several disadvantages. They require increased inventory of parts and the manipulation and installation of both the separate reel locks and the springs require separate steps. In certain of these prior locking mechanisms, the springs are extremely tiny. Thus, the springs are difficult to manipulate by hand, and are virtually impossible to install by automated procedures. Moreover, the presence of multiple, separate pieces results in increased material and installation costs and increases the possibility that the pieces may become separated after installation, either in transportation, in use, or if the cassette housing is taken apart for any reason after it has been assembled.
The aforementioned U.S. Pat. No. 4,232,840 recognized the disadvantages of installation encountered in the prior locking mechanisms which utilized either tiny separate springs or large individual springs. In an attempt to overcome these installation problems occasioned by such separate elements, this Letters Patent disclosed locking mechanisms in which both of the reel locks were joined together by a single relatively large resilient element which was molded integrally with and joined both of the reel locks so as to form a single element containing both of the reel locks and the resilient element. This interconnecting resilient element formed the spring for both reel locks.
However, this single, integral reel locking mechanism also suffers several disadvantages. One disadvantage occurs in the installation of the element in the cassette. Careful manipulation is required both to insure simultaneous positioning of both reel locks due to the fact that they are attached together, and also to insure that the resilient element which forms the spring and joins the reel locks is properly positioned and does not interfere with or disrupt the other locking mechanism elements. This is because the resilient spring element which couples both of the reel locks is of considerable size and occupies a substantial portion of the already restricted and compact area which is available for the locking mechanism. Another disadvantage is that a substantial force must be exerted on the locking mechanism to move the reel locks from the reel engaging to the disengaging position. This is due to the simultaneous action of the single resilient spring on both of the locks, the location at which the spring is coupled to the locks, the direction in which the spring forces bear against the locks, and the size of the spring itself.
A locking mechanism incorporating the principles of the present invention overcomes these several aforementioned disadvantages. A locking mechanism incorporating the principles of the present invention eliminates the need for separate reel locks and springs and, thus, reduces the number of parts. Such reduction in the number of parts in the present invention reduces both material and installation costs, reduces the amount of parts needed to be kept in inventory, and not only facilitates hand assembly of these mechanisms, but also facilitates assembly of these mechanisms by automated procedures. A locking mechanism incorporating the principles of the present invention also reduces the likelihood of separation of parts, either in use, in transportation or upon disassembly of the casing. A locking mechanism incorporating the principles of the present invention may be readily installed in previously configurated cassette housings without the need for any redesign of such housings to accept the reel locks and mechanisms. A locking mechanism incorporating the principles of the present invention is operable with a minimum of force and under the environmental conditions normally encountered by tape cassettes and is spaced from and located relative to the locking mechanism elements so as not to interfere with their operation.
In one principal aspect of the present invention, a reel locking mechanism for a tape cassette comprises at least one cassette housing half, a reel lock having means for engaging a reel in the cassette to prevent rotation of the reel, and mounting means for stationarily mounting the reel lock on the housing half, but allowing rotation of the reel lock on the housing half between reel engaging and disengaging positions. Spring means includes a resilient arm extending angularly to the reel lock and having one end formed in integral, one-piece relationship to the reel lock. The other end of the arm is free and unattached. Spring engaging means is mounted stationarily on the housing half and the resilient arm slidably contacts the spring engaging means when the reel lock is rotated between the reel engaging and disengaging positions to urge the reel lock toward the reel engaging position.
In another principal aspect of the present invention, the aforementioned reel locking mechanism includes a pair of such reel locks for respectively engaging each of the reels in the cassette. Each of the reel locks includes one of the resilient arms and each of the resilient arms operates independently of each other to urge their respective reel locks toward the reel engaging positions of each reel.
These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.